New INTREPID trial data dispel concerns of radiation-induced microvascular lesions

LONDON — Microvascular changes induced by external-beam X-ray therapy for age-related macular degeneration regressed spontaneously and did not affect vision, according to a presenter here.

During a 3-year safety analysis conducted within the INTREPID trial, researchers took X-rays using the IRay Stereotactic Radiotherapy System (Oraya Therapeutics) as an adjunctive to anti-VEGF therapy with Lucentis (ranibizumab, Genentech), showing the potential to reduce the number of injections by 25% at 2 years.

“Focal areas of microvascular abnormalities were observed in 33 of the 122 eyes evaluated by year 3,” Timothy L. Jackson, MD, PhD, said during his presentation at the Euretina Congress. “Lesions were very small — normally 1 to 2 disc areas — were mainly located outside the foveal area, and identified as non-vision threatening, but in five of the cases, were located in the fovea and might have potentially affected vision.”

No significant between-group differences in vision were noted, according to Jackson. Disease activity, rather than micovascular changes, was responsible for any vision loss within the study. In addition, clear regression or near-full regression was noted in 18 of the cases, Jackson said.

“Microvascular changes do occur in response to radiation, but for the most part, these do not affect the visual outcome,” he said.

In many cases, the lesions are not visible to physicians by fundus examination and can only be detected by computerized image-reading systems, according to Jackson.

Disclosure: Jackson receives research grant support by Allergan, Novartis, Crya and Retina AG and is a consultant advisory board member of Alcon, Bausch + Lomb, Dorc, Mesoblast and ThromboGenics.